<!doctype html>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<iframe id="iframe" src="/common/blank.html"></iframe>
<script>
promise_test(async (t) => {
  // Wait for after the load event so that the navigation doesn't get converted
  // into a replace navigation.
  await new Promise(r => window.onload = () => t.step_timeout(r, 0));
  let start_length = navigation.entries().length;
  let start_index = navigation.currentEntry.index;

  await iframe.contentWindow.navigation.navigate("#a");
  await navigation.navigate("#1").finished;
  await navigation.navigate("#2").finished;
  await navigation.navigate("#3").finished;
  await iframe.contentWindow.navigation.back().finished;
  assert_equals(navigation.entries().length, start_length + 3);
  assert_equals(iframe.contentWindow.navigation.entries().length, 2);
  assert_equals(navigation.currentEntry.index, start_index);
  assert_equals(iframe.contentWindow.navigation.currentEntry.index, 0);

  let top_entry_0_before = navigation.entries()[start_index];
  let dispose_promises = [];
  for (let i = start_index + 1; i < navigation.entries().length; i++) {
    dispose_promises.push(new Promise(r => navigation.entries()[i].ondispose = r))
  }

  // This push navigation should truncate in the top window.
  await iframe.contentWindow.navigation.navigate("#b").finished;

  // entries() should be updated in both frames, and all forward entries in the
  // top window should have dispose events, even though that wasn't the window
  // that navigated.
  await Promise.all(dispose_promises);
  assert_equals(navigation.entries().length, start_length);
  assert_equals(iframe.contentWindow.navigation.entries().length, 2);
  assert_equals(navigation.currentEntry.index, start_index);
  assert_equals(iframe.contentWindow.navigation.currentEntry.index, 1);
  assert_equals(navigation.entries()[start_index], top_entry_0_before);

}, "Dispose events should fire when entries are removed by a navigation in a different frame");
</script>
